**3.1 Data on the base gases**

For the base gas data, gas properties taken from the DVGW worksheet G 260 appendix 1 and sample values from the GASCALC computer program from e.on Ruhrgas AG have been used. The data are summarized in Table 4. Based on the technical characteristics of combustion of the base gases, the calorific ranges for the processed biogas were determined. Here, the calorific values for the calculations were assumed to be quantity-weighted averages and a + / - 2 percent band was placed around these (Tab. 5). In this way, in the following sections admixtures whose corresponding calorific values lie in this interval will be determined.


Table 4. Base gases

5,6 Vol.-%.

Methane volume

Carbon dioxide

Oxygen volume

Nitrogen volume

Hydrogen volume

Calorific value HS,n

pipes, fittings and equipment.

Wobbe Index

L gas H gas

fraction ϕCH4 Vol.-% ---

fraction ϕO2 Vol.-% 3.

fraction ϕN2 Vol.-% ---

fraction ϕH2 Vol.-% 5.

WS,n

Table 7. Requirements for processed biogas

Conditioning of Biogas for Injection into the Natural Gas Grid 377

processing to at least a minimum methane content of 94 vol -% is assumed. Together with the fractions of oxygen and nitrogen, the biogas has a maximum carbon dioxide content of

Butane: 1,5

Since methane is the main combustible component of biogas, the concentration largely determines the technical combustion characteristics

(H2 not taken into account)

This limit applies to dry

According to G 486-B2 for pressures > 100 bar

G 262 (in gases produced by fermentation usually not

Maximum + / - 2% variation to

(see G 685, thermal billing)

(HS,n, WS,n),

networks (G 260)

(<100 bar),

present)

for details see here

the distributed gas

Total range

Parameter Abbreviation Unit Limit Comment

volume fraction ϕCO2 Vol.-% 6. G 262

Relative density d 0,55-0,75 G 260

kWh/

kWh/

otherwise 0.5%. German natural gas grids are considered to be dry.

m³ 8,4-13,1

m³ 10,5-13,0 12,8-15,7

According G 260, the maximum permissible O2 volume fraction is 3% in dry networks,

It is important to note that CO2 and O2 in combination with moisture can lead to corrosion in

In addition to the above conditions, of course the information on sulphur compounds and other impurities and accompanying substances given in G 260 is also to be noted. The data

LPG mole fraction xLPG mol.-% Propane: 3,5 (6)


Table 5. Calorific value ranges
